Miss Gao likes __________ a bus to work.[ ]
A. having
B. bringing
C. taking
D. leaving
答案:C
等比数列{an}的公比q>0.已知a2=1,an+2+an+1=6an,则{an}的前4项和S4=______.
关于牙龈癌(如图)的叙述,哪项是错误的()
A.多为鳞状细胞癌
B.男性多于女性,以溃疡型多见
C.早期向牙槽突及颌骨浸润
D.下牙龈癌发病率高于上牙龈癌
E.上牙龈癌比下牙龈癌转移早